1. Field of the Invention
This invention relates to a latch assembly for locking a closing member such as a door or a lid to a box-like body or a stationary frame.
2. Prior Art
Japanese Utility Model Publication No. 157,864/1989 discloses a latch assembly, which comprises a latch case secured to a closing member and having a front plate member, bearing arm means projecting from the front plate member, a latch member pivoted by a pivotal pin to the bearing arm means and having on one side a guide projection for engagement and disengagement with respect to a lockable member on the side of a stationary frame, the guide projection having a stem portion thereof formed with a locking recess extending toward the pivotal pin, the lockable member being engaged and disengaged with respect to the locking recess, the latch member being provided on the side opposite the guide projection with an engagement projection, and a lock lever pivoted by a separate pivotal pin to the bearing arm means and having a free end provided with a lock projection for engagement and disengagement with respect to the engagement projection of the latch member, the latch member being rotationally urged toward an unlocked position by a torsion spring having a coil portion fitted on the pivotal pin, the lock lever, rotationally urged by a separate torsion spring having a coil portion fitted on the pivotal pin to maintain engagement between the engagement projection of the latch member and the lock projection of the lock member.
In this latch assembly, at the end of a closing operation of the closing member, the guide projection of the latch member is brought into contact with the lockable member of the stationary frame, and during further closing of the closing member latch member urged by the lockable member is rotated about the pivotal pin. When the lockable member is engaged in the locking recess to a predetermined extent, the lock projection of the lock lever is engaged with the engagement projection of the latch member, thus locking the closing member to the stationary frame. In this latch assembly, the latch member is provided with a single engagement projection. Therefore, the rotational angle of the latch member from the waiting position to the lock position is fixed.
Therefore, if the relative positions of the lockable member and latch member are shifted due to deformation or mounting position shift of a hinge coupling, the closing member to the stationary frame or a shift of the mounting position of a guide rail for the closing member or deformation of the lockable member, the closing operation of the closing member is over before the latch member is rotated for the predetermined rotational angle noted above, i.e., without the lockable member received in the locking recess to a sufficient extent. In such a case, defective or incomplete lock of the closing member would result.